
EXPERIMENTS ON DIGESTION OF FOOD BY MEN. TOF 
subject received 463 grams of protein in the food, of which 11 
grams were excreted by the intestine. This latter amount, 
which is here taken as representing the undigested protein, 
makes 2.4 per cent. of the total protein. Subtracting the 11 
grams of undigested protein from the 463 grams of protein 
eaten, the remainder, 452 grams, makes 97.6 per cent. of the 
total. This is taken as the measure of the protein digested, 
and is thus the coefficient of digestibility of the protein in this 
experiment. By comparing the coefficients of digestibility, 
as found in a number of similar experiments, averages are 
obtained for general use. 
Statements regarding the methods of estimating the fuel 
value are given on pages 177, 178. 
THE DETAILS OF THE EXPERIMENTS. 
The tables and descriptions which follow give accounts of 
fourteen individual experiments made with several different 
persons. The subject of Nos. 1-5 and 9-12, inclusive, was the 
laboratory janitor who acted as the subject of respiration ex- 
periments Nos. 1 and 2, above described. Experiment No. 6 
was made with three chemists who ate together of the same 
food. As this experiment involves the measurement of the 
income and outgo of nitrogen, and was carried out with 
unusual care, it is treated by itself. The subject of Nos. 7 
and 8 was an infant. The experiments are reported beyond 
by Mr. Bryant. ‘The subjects of Nos. 13 and 14 were gentle- 
men engaged in experimental inquiry. 
The results of experiments Nos. 1-5 and 9-14 are given in 
some detail in table 49. In connection with this are descrip- 
tions of the individual experiments. 
